Mark Zuckerberg just lost $9 billion in wealth

Mark Zuckerberg's wealth has tumbled by more than $9 billion over the past 48 hours.

This weekend, the Facebook founder was the fourth richest man in the world. Now, he will be sixth or seventh.

His wealth loss over the past two days is greater than the entire net worths of all but 170 of the world's more than 1,000 billionaires.

Mark Zuckerberg

Stephen Lam | Reuters

Mark Zuckerberg's wealth status has changed — he's lost more than $9 billion in stock wealth over the past 48 hours.

Zuckerberg, who owns about 400 million shares of Facebook, has seen his wealth drop to around $66 billion from $75 billion since the stock closed on Friday, according to the Bloomberg Billionaire's Index and Forbes. This weekend, he was the fourth richest man in the world. Now, he will be sixth or seventh.

Zuckerberg has already sold around 5 million shares this year — before the stock drop. The sale was part of his announced plan to accelerate his philanthropic giving by setting up scheduled sales of the stock.

Last fall, he said he planned to sell 35 million to 75 million shares over the following 18 months. Those 75 million shares are now worth $1.7 billion less.

His wealth loss in the past two days is greater than the entire net worths of all but 170 of the world's more than 1,000 billionaires.